The objective of the study is to evaluate the ovarian response of juvenile rhesus monkeys subjected to stimulation with exogenous hormones. The demonstrated ability to superovulate juvenile females could reduce generation times in efforts to propagate inbred, transgenic or other valuable founder animals. Five juveniles were subjected to our standard ovarian stimulation protocol involving down regulation with the GnRH antagonist, Antide, followed by administration of recombinant human FSH and LH. Ovarian responsiveness is monitored by ovarian ultrasonography in the size and number of follicles and by measurements of systemic levels of estradiol. A bolus injection of human chorionic gonadotropin is used to induce final preovulatory maturation events and oocytes are harvested by laparoscopic aspiration. The maturity and fertilizability of harvested oocytes are then assessed. The results obtained from juvenile females are compared with those from adults.